1. Field of the Invention
This invention relates to a new energy attenuation device for a fluid-conveying line and to a method of attenuating energy in such a line. The invention is particularly suitable for placement in the hydraulic system of a power steering unit of a vehicle, although the invention would also be suitable for any other fluid-conveying system.
2. Prior Art Statement
In hydraulic systems where the operating fluid is circulated by a pump, the pulsations of pressure that are generated by the pump are transmitted through the conduits and result in noise and/or vibration being produced by the hydraulic fluid. In the case of power steering fluid in vehicles, such noise and/or vibration is caused, for example, when vehicles are being parked or unparked at idle or very low speeds of movement thereof, such as barely moving into and out of a parking space or the like while the wheels of the vehicle are being turned by the power steering mechanism thereof. In particular, substantial noise and/or vibration (shutter) can be produced in such a situation when the power steering fluid passes through the power steering mechanism from the fluid pump to the effective steering structure. Further background in this area can be obtained from U.S. Pat. No. 3,323,305, Klees, whereby this U.S. Patent is being incorporated into this disclosure by this reference thereto.
Systems are known for controlling the resonation of pressure waves in fuel injection systems. For example, U.S. Pat. No. 5,168,855, Stone, passes fluid through check valves that are provided with a flow restriction either directly therein or in a bypass line. U.S. Pat. No. 5,509,391, DeGroot, provides a spool valve assembly for controlling flow between inlet and outlet ports.